A dielectric resonator is an electronic component that exhibits resonance for a narrow range of frequencies, generally in the microwave band. Resonators are used in, for example, radio frequency communication equipment. In order to achieve the desired operation, many resonators include a “puck” disposed in a central location within a cavity that has a large dielectric constant and a low dissipation factor.
The combination of the puck and the cavity imposes boundary conditions upon electromagnetic radiation within the cavity. The cavity has at least one conductive wall, which may be fabricated from a metallic material. A longitudinal axis of the puck may disposed substantially perpendicular to an electromagnetic field within the cavity, thereby controlling resonation of the electromagnetic field.
When the puck is made of a dielectric material, such as ceramic, the cavity may resonate in the transverse electric (TE) mode. Thus, there may be no electric field in the direction of propagation of the electromagnetic field. While many TE modes may be used, dielectric resonators may use the TE011 mode for applications involving microwave frequencies. Using the TE011 mode as an exemplary case, the electric field will reach a maximum within the puck, have an azimuthal component along a central axis of the puck, generally decrease in the cavity away from the puck, and vanish entirely along any conductive cavity wall. The magnetic field will also reach a maximum within the puck, but will lack an azimuthal component.
While the dielectric resonator will store an electromagnetic field, it may also produce a considerable amount of heat. Coupling the puck to another object may compensate for overheating. When two solid bodies come in contact, heat flows from the hotter body to the colder body. As this flow is not instantaneous, a temperature drop occurs at the interface between the two surfaces in contact. The ratio between this temperature drop and the average heat flow across the interface is known as the “thermal contact resistance.” When this resistance is minimized, heat flows rapidly.
Consequently, a dielectric resonator may use a “support” for heat transfer, such that heat is transferred from the puck to the support and out of the resonator. A designer would characterize the material in the support by its thermal conductivity, a parameter that measures its ability to conduct heat. Unfortunately, materials with very high thermal conductivity and very low electrical conductivity are often prohibitively expensive for use in such supports. As a result, current implementations fail to effectively radiate heat to the external environment, particularly in high power applications, thereby resulting in impaired operation or failure of resonators due to overheating.
Accordingly, there is a need for a thermally efficient, cost-effective support for a dielectric resonator. In particular, there is a need for a support that has relatively low thermal contact resistance, permitting rapid transfer of heat, but also has electrical characteristics that would not interfere with the operation of the resonator. Conventional techniques can only drain generated heat slowly, so they are not suitable for dielectric resonators used in high power operations that may produce rapid temperature spikes in the central pucks.